If you fire a gun in space, do the bullets will never stop until only hit an object or drag by gravity

Will the bullets will go forever if didnt hit anything?

Every object continues in its state of rest, or of uniform motion in a straight line, unless compelled to change that state by external forces acted upon it.

since you stated that it isnt affected by gravity, yes it will continue forever

Not really, although the time required for the bullet to stop due to gravity alone would be near infinity. Gravity exists *everywhere* in the universe and not always near a star, planet, nebula, etc.,. Theoretically even the range of gravity from Earth is infinite. Taken all together, the multitude of gravity fields throughout the universe would eventually effect the bullet.

What do you mean by "stop"?

Such a term has no meaning at all in outer space.

It is only relevant near the earth in that we mean "stops moving with respect to the earth".
And there is no such body in outer space.

We can never say " a body is moving" or " a body is moving at speed x" nor " a body has stopped in space"

So only Newton's law is applicable. A body will continue in a straight line with constant speed unless acted upon by a force.

And all that we can determine is that the velocity CHANGES as a result of the force. We have no measure of what it IS.

Yes they will continue indefinitely . Objects in motion tend to stay in motion while objects at rest tend to stay at rest. The bullet would travel forever unless it was acted upon by an external force (gravitational pull, solar winds, etc.)

Eventualy gravity but it will continue until then.
The time it hits gravity depends on the neares mass form & the size of the mass.

You could accidently shoot a person :o

yes it doesnt stop. untill when any kind of drag force not applying.